@Phil1934, for a driveway, best to consult the fire department of AHJ. It may not have to be H-20, hopefully not HS-20. Some localities may require what's known as an EV truck (emergency vehicle).
If it's a bridge over a waterway, hydraulics is the most important information to gather. There are 2 reasons for this. The first is for the obvious reason that you need to bridge the waterway with the structure without negatively affecting the hydraulics but the 2nd (and more time consuming) reason is because of the environmental permits that will then be triggered. These permits can typically take years to get whereas the design of the bridge may only take a few months. Placing intermediate piers within the waterway will only exacerbate the problem and delay the process but of course there are times that it is unavoidable and necessary. On the topic of the hydraulic requirements, in my part of the country (not sure if this is true for other parts) we design the bridge for the following parameters and behaviors:
FEMA Floodplain:
Q100 - Hydraulics need to be met with 2ft freeboard
Q200 - Satisfy Strength Design with Scour
Q500 - Bridge stability needs to be met with Scour
Non FEMA Floodplain is the same but uses Q50, Q100, and Q200, respectively.
Soil Information is absolutely necessary. Need borings.
Survey information as you will need to know where the Right of Way is and what the existing topography of the site is.
Current and future prediction of traffic counts. This will govern the width of the bridge as it ties into the greater picture of the roadway design.
Geometrics of the roadway and bridge need to be set prior to the start of the structural design.
Utilities are another big one. It's usually not a big deal for a new bridge design. Street light and traffic signal lines usually always are included but are owned by the same agency that owns the bridge so it's usually pretty straightforward. Power, telecommunications, fuel, water, sewer lines complicate the process a bit more since there is a fair amount more coordination to do but these agencies know that you are doing them a favor so they are easier to work with and will respond back within the design timeframe. If you are retrofitting the bridge/widening the bridge and there are existing utility lines that will be affected then you're screwed! Once utility agreements are in place the utility agency suddenly becomes difficult to work with, unresponsive, very picky about what you do with their lines, and has a million requests and opinions. I have seen utility companies delay the design process by years and cause millions of dollars worth of construction change orders.
